Unpacking Contested Multilateralism: Legitimacy Crises, Post-Politics, and Fragmentation in the Global Climate Regime

The crisis of multilateralism is widely debated, yet scholars approaching its complexity often talk past one another and stick to specific conceptual perspectives. We hold that, to better understand and address this crisis, we need to disaggregate it into core components and developments. This article focuses on three such key components by uniting prominent but largely disconnected literatures: legitimacy crises of international organizations (IOs), post-political developments within IOs, and conflictive fragmentation beyond them. We ask: how are these major challenges to multilateralism, so far analyzed separately, causally interconnected? To address this question, we develop a novel analytical framework arguing that a legitimacy crisis is not merely one symptom of contested multilateralism among others. It is a causal starting point that can trigger two distinct forms of authority shifts for an IO in crisis: the displacement of political debates and policy functions inside the IO (post-politics), and the creation of rival institutional arrangements outside it (fragmentation). To illustrate the framework’s plausibility, we explore two UNFCCC legitimacy crises (2000/2001 and 2009), drawing on elite interviews, conference bulletins and scholarly literature. The evidence suggests a contra-cyclical pattern: the first crisis was followed predominantly by conflictive fragmentation outside the UNFCCC, while the second gave rise mainly to post-political consequences within it, such as the shift from binding commitments in the Kyoto Protocol to the voluntary architecture of the Paris Agreement. These findings motivate a broader research program on the conditions under which authority migrates within and outside IOs in the contested liberal international order.